1. Field of the Invention
The present invention relates to controller of an electric power steering apparatus comprising a steering assist control mechanism having an electric motor giving a steering assist force to a steering system, abnormality detection means for detecting an abnormality of this steering assist control mechanism, and abnormality data storage means for storing the abnormality analysis data in the storage means when the abnormality of the steering assist control mechanism is detected by this abnormality detection means.
2. Description of the Prior Art
In general, as a controller of the conventional electric power steering apparatus, for example, there has been known an electric power steering torque sensor, which is constituted by data detection means for detecting, for example, data usable for failure analysis of a torque sensor and temporary storage means for temporarily storing data detected by the data detection means, wherein data when a steering assist force command from among data stored in the temporary storage means exceeds a rated value, that is, data only when a handle operation by a driver is actually performed is written in a backup memory, thereby to exclude unnecessary data when analyzing a failure, and useful data only is retained so as to save a capacity of the backup memory, and further, the backup memory is constituted by an overwrite memory and an archival nonvolatile memory, and in case the size of data stored in the temporary storage means exceeds a setting range, that is, if and only when there is a high possibility of some abnormality being generated, data is additionally retained in the archival nonvolatile memory (for example, see JP2000-337977A).
However, in the conventional example disclosed in the aforementioned Patent Document 1, though analysis data is stored in the archival nonvolatile memory if and only when there is a high possibility of some kind of abnormality being generated, in case the data exceeds a retainable number of pieces of the archival nonvolatile memory, an overwrite is made in the archival nonvolatile memory, and this causes an unsolved problem of initial analysis data being erased.
That is, in case a user makes a request for repair to a dealer or a repair plant after finding out the failure of a torque sensor, when the abnormality exceeds a retainable number of times of the archival memory including the time during the repairing operation, the initial analysis data is overwritten so that the initial abnormality data necessary for analysis is lost to cause an unsolved problem, thereby becoming an obstacle to the abnormality analysis.
Hence, the present invention has been carried out aiming at the unsolved problem of the foregoing conventional example, and an object of the invention is to provide a controller of an electric power steering apparatus, which can reliably retain initial abnormality analysis data necessary for failure analysis.